Multi-tasking - Processes and Threads

[BMW]

I have got multi-tasking up and running (with processes), and I was wondering how to implement threads.

If I understand the wiki (Process and Threads) correctly, implementing thread support should be very simple - adding a thread could simply add a 'process' which uses the same address space as the parent process but has a separate stack.

This left me wondering, what's the catch?

[Brendan]

Hi,

I have got multi-tasking up and running (with processes), and I was wondering how to implement threads.

If I understand the wiki (Process and Threads) correctly, implementing thread support should be very simple - adding a thread could simply add a 'process' which uses the same address space as the parent process but has a separate stack.

This left me wondering, what's the catch?

I find it much easier to think of a process as a container that contains one or more threads.

Basically; a process has a virtual address space and a few other things that the scheduler doesn't care about, and contains one or more threads that the scheduler does care about. When a process is created, its initial thread is also created (and it's this initial thread that begins executing at the process' entry point). If a process has no threads (e.g. its last remaining thread has terminated) then the "thread container" is destroyed.


Cheers,

Brendan

[BMW]

I find it much easier to think of a process as a container that contains one or more threads.

Basically; a process has a virtual address space and a few other things that the scheduler doesn't care about, and contains one or more threads that the scheduler does care about. When a process is created, its initial thread is also created (and it's this initial thread that begins executing at the process' entry point). If a process has no threads (e.g. its last remaining thread has terminated) then the "thread container" is destroyed.


Cheers,

Brendan

That makes much more sense. Thanks.